Glare occurs when lighting is brighter than the general environment and can cause eye fatigue, discomfort, and reduced visibility. There are two main types: direct glare from bright luminaires in the field of vision, and reflected glare from reflections off glossy surfaces. Glare is evaluated using various systems that measure luminance levels and angles to determine if lighting installations meet comfort standards for most people. Methods for minimizing glare involve shielding luminaires, increasing side lighting, and using curtains or blinds on windows.

1. Environment and glare

2. Glare is experienced, when Lamps, Windows,
Luminaries, other areas are brighter than general
brightness in the environment.
Glare by definition brightness within the field of
vision that causes discomfort, annoyance interference
and eye fatigue.
It reduces the visibility of an object.
This is the common fault of lighting installations.

3. Effects of glare
• injures the eye
• disturbs the nervous system
• causes annoyance, discomfort & fatigue
• reduces efficiency of work
• interferes with clear vision
• risk of accident increases

4. Types of glare
• Direct Glare
• bright luminaire in the field of vision
• Reflected Glare
• reflection from a glossy surface
Direct glare results from bright luminaire in the field
of vision.
Reflected glare arises due to reflection of such a
source from a glossy surface it is more annoying than
direct glare can be avoided by appropriate choice of
interiors

5. Glare Evaluation Systems
• American system (VCP) visual comfort probability
• British system (Glare Index)
• European system (Luminance Curves)

6. Glare Evaluation
This is expressed as percentage of people considering
an installation comfortable as viewed from one end.
Glare tables list various proportions and layout of
room for glare free lighting.
Figure of merit is based on a source of 1000 lm.from a
luminaire.
If VCP ≈ 70% then the system is said to be glare free.
Standard code for Luminaire base lamp. dep. on room
dimensions, mounting height and a Empirical
shielding angle

7. Quality class is expressed from A to E type is based on
Luminaire orientation.
Type 1. Luminous sides when Luminous side plane>
30 mm
Type 2. Elongated – length/width >2

8. Luminance limits for luminaires critical angles, γ are
45º < γ < 85º.

9. different types of lamps effective shielding angle.
Quality class A denotes very high level; B denotes
high, C medium D low and E very low.

10. How is Glare evaluated?
Determine luminance of the source between 45º - 85º
2. Determine the quality class and illuminance
required.
3. Select the curve – class / level.
4. Determine. Max. Angle to be considered from
length & height and plane of eye level & plane of
luminaires.
5. Horizontal limit based on” a / h”, part of the line
( or curve) to be ignored.
6. Compare luminance of one luminaire with selected
part of the limiting curve.

11. glare in dicer and curves to be used for different
levels of illuminance and quality

12. luminaire curves to be employed for different levels
for Type I luminaire

13. luminaire curves to be employed for different levels
for Type II luminaire.

14. Glare from windows can be
prevented by using
• curtains
• blinds
• louvers
Glare from windows is of two types :
• veiling reflections
• reflected glare

15. Techniques for minimization of
glare from luminaires
• not locating luminaires in forbidden zone
• increase light from sideways
• luminaires having large surface area

16. categories of lighting
• general lighting
• local lighting
• combination of local & general lighting
• Combination of general & local lighting are
preferred to avoid glare

17. Summary
Effects of glare :
• injures the eye
• disturbs the nervous system
• causes annoyance, discomfort & fatigue
• reduces efficiency of work
• interferes with clear vision
• risk of accident increases
Types of glare :
• Direct Glare
• bright luminaire in the field of vision
• Reflected Glare
• reflection from a glossy surface